Lower valent titanium-aluminum halides



United States Patent 3,275,568 LUWER VALENT TlTANlUM-ALUMlNUM HAHDESRobert Holroyd Stanley, Hartburn, Stochton-on-Tees, and

Derek Howden, Nunthorpe, England, assignors to British Titan ProductsCompany Limited, Billingham, England, a corporation of the UnitedKingdom No Drawing. Filed Nov. 13, 1962, Ser. No. 237,346 Claimspriority, application Great Britain, Nov. I3, 1961, 40,569/61 libClaims. ((1 252-442) The present invention relates to a process for thepro duction of mixtures or compounds containing titanium having avalency lower than four, and in particular to mixtures or compounds ofthis type wherein the titanium is present as a halide. The mixtures orcompounds also contain an aluminium halide.

Lower halides of titanium in which the valency of titanium is less thanfour, for example, titanium trichloride, are commonly present togetherwith an aluminium halide in polymerisation catalysts of the Ziegler orNattatype, which are widely used in the polymerisation of unsaturatedhydrocarbon compounds such as olefins, for example ethylene andpropylene.

These compounds, i.e. lower halides of titanium and aluminium halides,are also of value as additives to the vapour phase oxidation of atitanium tetrahalide to produce pigmentary titanium dioxide, since theyact as nucleating agents for the titanium dioxide formed and ensure thatthe pigmentary product is predominantly rutile.

The production of aluminium halides and lower halides of titanium by thereduction of a tetra-halide with aluminium has been previouslydescribed, particularly in relation to the production ofZiegler/Natta-type catalysts. Various methods of carrying out thisreduction have been disclosed, for example, by:

(a) Heating together aluminium and titanium tetrachloride at atemperature of about 200 C.

(b) Heating together aluminium and titanium tetrachloride in a liquidhydrocarbon at a temperature in the range of about 80 C.180 C. for longperiods.

(c) Ball milling aluminium and titanium tetrachloride together forprolonged periods at a temperature in the range of about 20 0-100 C.

These methods have the disadvantage that they are time consuming and/orrequire special equipment.

It is an object of the present invention to provide a process for theproduction of mixtures or compounds containing a lower halide oftitanium and an aluminium halide.

It is also an object of the invention to provide such a mixture orcompound which shows excellent activity when used as a component of aZiegler/Natta-type catalyst.

Accordingly, the present invention is reducing a titanium tetrahalidewith aluminium in the presence of free halogen.

The titanium tetrahalide is preferably titanium tetrachloride and thehalogen is preferably chlorine, although other halides and halogens maybe used if desired, particularly if a liquid solvent or diluent is usedto provide a liquid reaction medium. Normally the halogen will be thesame as that combined in the titanium tetrahalide. For example, the useof titanium tetraiodide and iodine is also contemplated.

The amount of tetrahalide used is preferably at least sufiicient toreact with all the aluminium present, i.e. at least a stoichiometricamount of the tetrahalide. Indeed, it is advantageous to use an excessof the tetrahalide in order to ensure that no free aluminium remains inthe reaction product, since this might be undesirable; for ex- 3,2755%Patented Sept. 27, 1966 ample, the aluminium might contaminate thepolymer produced.

The amount of free halogen present may vary widely. As an example of theamounts of free halogen which may be used, it may be noted that suitableamounts may be within the range from 1 to 50 moles of halogen per molesof titanium tetrahalide. Amounts of at least 3 moles of halogen per 100moles of titanium tetrahalide are particularly contemplated.

The reaction may be carried out if desired in the presence of an addedliquid diluent for example hydrocarbons such as aromatic hydrocarbons orchlorinated hydrocarbons. Examples of these are benzene, toluene,chlorobenzene, dichlorobenzene, and tetrachloroethylene.

Alternatively, where the tetrahalide is liquid, as in the case oftitanium tetrachloride, an excess of this may be used to provide aliquid reaction medium.

Since the reaction is exothermic it is normally carried out under refluxto prevent loss of any tetrachloride diluent as the reaction proceeds.The reaction will generally commence at room temperature, usually aftera short induction period.

If the reaction is carried out with only suflicient titanium tetrahalideto complete the reaction (and without additional diluent) a solid purplemass is formed in the reaction vessel. The addition of further titaniumtetrahalide or liquid diluent may cause further reaction within thismass.

In the preferred method, the reaction is carried out in the presence ofan excess of titanium tetrahalide or other liquid diluent. Thisdecreases the violence of the reaction. A slurry is obtained from whicha purple or brown solid may be recovered, for example by filtration ordistillation followed by drying of the residue.

Since the lower halides of titanium are reactive in the presence ofoxygen or moisture the reaction and recovery are avantageously carriedout in the absence of oxygen or moisture, e.g. under an inert atmospheresuch as nitrogen or argon.

A convenient method of introducing the halogen into the reaction mixtureis to dissolve it in the titanium tetrahalide or in any liquid diluent.This may be done, for example, by adding it to the titanium tetrahalideor diluent before adding this to the aluminium. Alternatively, thehalogen may be added after mixing the aluminium and the titaniumtetrahalide (and any additional diluent) in the reaction vessel.

It is preferred to use only sufficient halogen to initiate the reactionsince an excess of halogen may reduce the yield of titanium trihalide.This may be effected by adding the halogen to the titanium tetrahalideor any diluent before the reaction starts, and then adding no furtherhalogen until the reaction is complete.

It is, of course, preferred that the aluminium be present in afinely-divided form to ensure the most rapid and complete reaction.

If it is desired to use the product of the reaction as a component of aZiegler/Natta-type catalyst, the dry material may be recovered by knownmethods and used in a known manner as a catalyst component. For example,it may be milled, suitably by either dry ball milling or ball milling ina liquid vehicle. Where a liquid vehicle is used this is preferably theliquid in which the polymerisation process is to be carried out. Aftermilling the product may be introduced into a polymerisation vessel andthe other component of the catalyst may then be also convenientlyintroduced into the vessel followed by the unsaturated hydrocarbon thatis to be polymerised. Such other component of the catalyst is suitablyan organo-metallic compound such as an aluminium alkyl or aluminiumalkyl halide and in particular an aluminium trialkyl or triaryl, e.g.triethyl aluminium, tri-n-propyl aluminium, tri-n-butyl aluminium, ortri-phenyl aluminium. Alkyl or aryl compounds of other metals in groups1 to 3 of the Periodic Table may be used if desired.

If it is desired to use the product of this invention in the vapourphase oxidation of a titanium tetrahalide, this may be done, forexample, by reacting a calculated proportion of aluminium with an excessof titanium tetrahalide in the presence of halogen and using the productas a feed or as an addition to the feed to the vapour phase oxidationreactor. Under such circumstances both the aluminium halide and thelower halide of titanium present in the mixture form nucleating agentsfor the titanium dioxide formed during the oxidation process.

The following examples describe some methods of carrying out the processof the present invention.

Example 1 To a flask filled with dry argon and fitted with a refluxcondenser was added 9 g. of aluminium powder, having a mean particlediameter of about 0.5 micron, followed by 190 g. of redistilled titaniumtetrachloride. The titanium tetrachloride had been saturated withchlorine at room temperature, so that it contained about 18 mole percentof chlorine (i.e. 18 moles of chlorine per 100 moles of titaniumtetrachloride).

No reaction occurred for about minutes, after which some bubbling wasnoticed. A violent reaction then occurred with the evolution of aconsiderable amount of heat. Unreacted titanium tetrachloride vapour wascondensed in the reflux condenser and returned to the reaction mixture.As the titanium tetrachloride reacted a dark purple solid wasprecipitated in the flask.

To the flask was then added 100 g. of dry benzene. A vigorous reactionagain occurred, but further additions of benzene produced no furtherreaction.

The dark benzene slurry was filtered under argon, Washed five times with200 cc. of dry benzene, and then dried by heating for four hours at 100C. under reduced pressure.

The product was a pink/ brown solid. It was weighed, and it was foundthat the yield was 80% (based on the amount of titanium tetrachlorideused) of the theoretical yield if the reaction took place according tothe equation The catalytic activity of the product was tested in thefollowing manner. It was ball milled with a suitable quantity of dryn-heptane for 48 hours; a quantity of the resulting product, equivalentto 6.53 millimoles of titanium, was introduced into a flask, followed by19.59 millimoles of aluminium triethyl. Propylene was then passed intothe flask for three hours, after which the polypropylene formed in theflask was recovered and weighed. The weight of the polypropylene was 45g.; the catalytic activity of the product was therefore 54.7 moles ofpropylene per mole of titanium per hour.

This result showed that the product had excellent activity as apolymerisation catalyst.

Example 2 An experiment was carried out as described in Example 1,except in the following respects:

(1) 110 ml. of titanium tetrachloride were used (instead of the 190 g.of Example 1),

(2) 250 ml. of benzene were used (instead of the 100 g.

of Example 1),

(3) chlorine was bubbled into the reaction mixture for twenty minutesbefore the reaction began,

and in the estimation of the catalytic activity of the resultingproduct:

(4) the quantity of the product taken was equivalent to 9.9 millimolesof titanium (instead of the 6.53 millimoles of Example 1),

(5) the amount of aluminium triethyl was 19.8 millimoles (instead of the19.59 millimoles of Example 1).

41- The catalytic activity of the pro-duct was found to be 45 moles ofpropylene per mole of titanium per hour.

Example 3 An experiment was carried out as described in Example 1,except in the following respects:

(1) 330 ml. of titanium tetrachloride were used (instead of the 190 g.of Example 1),

(2) no benzene was used (instead of the g.

Example 1),

(3) chlorine was bubbled into the reaction mixture for fifteen minutesbefore the reaction beg-an,

and in the estimation of the catalytic activity of the resultingproduct:

(4) the quantity of the product taken was equivalent to 10.1 millimolesof titanium (instead of the 6.53 millimoles of Example 1),

(5 the amount of aluminium triethyl was 20.2 millimoles (instead of the19.59 millimoles of Example 1).

The catalytic activity of the product was found to be 22 moles ofpropylene per mole of titanium per hour.

Example 4 An experiment was carried out as described in Example 1,except in the following respects:

(1) 121 ml. of titanium tetrachloride were used (instead of the g. ofExample 1),

(2) 200 ml. of tetrachloroethylene were used (instead of the 100 g. ofExample 1),

(3) chlorine was bubbled into the reaction mixture for twenty minutesbefore the reaction began,

and in the estimation of the catalytic activity of the resultingproduct:

(4) the quantity of the product taken was equivalent to 9.9 millimolesof titanium (instead of the 6.53 millimoles of Example 1),

(5) the amount aluminium triethyl was 19.8 millimoles (instead of the19.59 millimoles of Example 1).

The catalytic activity of the product was found to be 16.4 moles ofpropylene per mole of titanium per hour.

Example 5 An experiment was carried out as described in Example 1,except in the following respects:

and in the estimation of the catalytic activity of the resultingproduct:

(5 the quantity of the resulting product taken was equivalent to 11.9millimoles of titanium (instead of the 6.53 millimoles of Example 1),

(6) the amount of aluminium triethyl was 23.8 millimoles (instead of the19.59 millimoles of Example 1).

The catalytic activity of the product was found to be 37.5 moles ofpropylene per mole of titanium per hour.

Example 6 To a flask filled with dry argon were added 9 g. of aluminiumpowder, having a mean particle diameter of about 0.5 micron, followed bytitanium tetrachloride. The titanium tetrachloride consisted of 22 ml.saturated with chlorine and then mixed with a further 88 ml. not treatedwith chlorine; since saturated titanium tetrachloride contains about 18mole percent of chloride, the titanium tetrachloride added to thealuminium contained about 3.5

mole percent of chloride. To the flask was then added 100 ml. ofhenzene.

The reaction mixture was left overnight.

The next morning it was found that the titanium tetrachloride had beenreduced by the aluminium and a dark purple solid similar to that ofExample 1 was present in the reaction mixture.

Useful results can also be obtained by using other titanium tetrahalidesin the above examples as starting material, such as titaniumtetraio'd-ide.

What is claimed is:

1. In the reaction in a liquid reaction medium of a titanium tetrahalideand aluminum metal to produce a lower valent titanium-aluminium halidecomposition, the improvement comprising introducing at least 1 mole offree halogen per 100 moles of tetrahalide into said reaction medium andinitiating said reaction in the reactive presence of free halogen.

2. A process according to claim 1 in which the amount of free halogen isfrom 3 to 50 moles per 100 moles of titanium tetrahalide.

3. A process according to claim 1 in which the tetrahalide is liquid andan excess of it is used to provide a. liquid reaction medium in thereaction chamber.

4. A process according to claim -1 in which a liquid diluent other thanthe tetrah-alide is introduced into the reaction chamber so as toprovide a liquid reaction medium therein.

5. A process according to claim 4 in which the liquid diluent is ahydrocarbon.

6. 'A process according to claim Sin which said hydrocarbon is selectedfrom the group consisting of benzene, toluene, chlorobenzene,dichlorobenzene and tetrachloroethylene.

7. A process according to claim 1 in which the titanium tetrahalide istitanium tetrachloride and the free halogen is chlorine.

8. A process for the production of material containing aluminiumchloride and lower chloride of titanium, comprising introducing into areaction vessel aluminium metal, an amount of liquid titaniumtetrachloride which is in excess of the amount required to react withall the aluminium metal, and from 1 to moles of tree chlorine per molesof titanium tetrachloride, these three reactants being intimatelyintermingled, reacting the aluminium metal with the titaniumtetrachloride in the presence of the free chloride to produce aluminumchloride and lowerchloride of titanium, and recovering from the reactionvessel material containing aluminium chloride and lower chloride oftitanium.

9. A process according to claim 8 in which there is also introduced intothe reaction vessel to provide a liquid react-ion medium therein aliquid hydrocarbon diluent.

10. A process according to claim 9 in which the liquid hydrocarbondiluent is selected from the group consisting of benzene, toluene,chloro'benzene, dichlorohenzene, and tetrachloroethylene.

References Cited by the Examiner UNITED STATES PATENTS 2,937,928 5/1960Hughes et al. 23-202 2,954,367 9/ 1960 Vandenberg 260-94.9 2,964,38612/1960 Evans et a1 23-402 3,010,787 11/ 1961 .Tornquist -23--873,017,401 '1/l962 Bo et al. 2'3-87 X 3,031,440 4/ 1962 Kaufman et a1.

3,032,390 5/1962 Caunt 23-51 3,061,410 10/ 1962 Toland 23--87 3,079,3712/1963 B0 260-94.9

OSOAR R. VERTIZ, Primary Examiner.

JOSEPH L. SCHOFER, MAURICE A. B'RINDISI,

Examiners.

M. B. KURTZMAN, E. STERN, Assistant Examiners.

1. IN THE REACTION IN A LIQUID REACTION MEDIUM OF A TITANIUMTERTRAHALIDE AND ALUMINUM METAL TO PRODCE A LOWER VALENTTITANIUM-ALUMINUM HALIDE COMPOSITION, THE IMPROVEMENT COMPRISINGINTRODUCING AT LEAST 1 MOLE OF FREE HALOGEN PER 100 MOLES OF TETRAHALIDEINTO SAID REACTION MEDIUM AND INITIATING SAID REACTION IN THE REACTIVEPRESENCE OF FREE HALOGEN.